Implement chats in a MAUI app with ChatGPT valid for a session

[erossini]

In my .NET 8 MAUI, I like to implement a chat with different ChatGPT users about different topics.

I saw your examples but none of them explains how to create more messages in the same chat with the same conversationId. I like to get a json to manage the answer from ChatGpt better. For example:

    using var api = new OpenAIClient();
    var messages = new List<Message>
    {
        new Message(Role.System, "You are a helpful assistant designed to output JSON."),
        new Message(Role.User, "Who won the world series in 2020?"),
    };
    var chatRequest = new ChatRequest(messages, Model.GPT4o, 
                                      responseFormat: ChatResponseFormat.Json);
    var response = await api.ChatEndpoint.GetCompletionAsync(chatRequest);
    
    foreach (var choice in response.Choices)
    {
        Console.WriteLine($"[{choice.Index}] {choice.Message.Role}: {choice} " + 
                          $"| Finish Reason: {choice.FinishReason}");
    }
    
    response.GetUsage();

In this example, there is no interaction with a user. chatRequest doesn't contain a conversationId and I can't find how to pass this value as a context for ChatGPT if I want to add a new message from the user.

Also, in the app, the user can leave the chat page and then open it later but the conversation should continue. Do you have any example for that?

Thank you in advance,
Enrico

[StephenHodgson]

Hi @erossini

There is a Conversation class you can use for exactly this purpose.

I use it like so:

    using var api = new OpenAIClient();
    var conversation = new Conversation(
        [
            new(Role.System, "You are a helpful assistant designed to output JSON."),
            new(Role.User, "Who won the world series in 2020?")
        ]);
        
    var chatRequest = new ChatRequest(conversation.Messages, Model.GPT4o, 
                                      responseFormat: ChatResponseFormat.Json);
    var response = await api.ChatEndpoint.GetCompletionAsync(chatRequest);
    conversation.AppendMessage(response.FirstChoice.Message);

You should be able to serialize this object to json if you wish to store a user session and return to it later :)

also, appending the message also works for tool calls and other function/roles.

you will need your own system of remembering and saving sessions though.

[erossini]

Thank you for this code and in advance for my next question 😁. That means I must have a global conversation object in my application and use it when it needs it, right?

So, the next question is: what if I want to move this logic in an API? How can I keep the conversation going?

[StephenHodgson]

not global, probably you can create one per session.

the conversation can be easily converted to json, and you'd store that locally or in our database somewhere.

you'll need to keep track of the session info yourself based on any info you'd like (userid, time, etc)

to continue the conversation just deserialize the conversation and append any new questions/messages to the conversation object and pass the whole thing back in the chat request. Be aware there is a context limit. (That's why most people have moved to assistants api since it handles most of this for you by default with threads, etc.)

[erossini]

Thank you. So, it is convenient to move to Assistant.

[StephenHodgson]

yes, prob more aligned with your needs. You'll be able to get a threadId. Most of the features are the same, just the API is slightly different.

[erossini]

I'm trying to create the Assistant and adding messages after the creation.

    var request = new CreateAssistantRequest(Model.GPT4o);
    assistant = await client.AssistantsEndpoint.CreateAssistantAsync(
        new CreateAssistantRequest(
            name: "English Teacher",
            instructions: "You are a personal English Teacher.",
            model: Model.GPT4o));

    var messages = new List<Message> { "Good morning! How is the weather?" };
    var threadRequest = new CreateThreadRequest(messages);

    chats = await assistant.CreateThreadAndRunAsync(threadRequest);

Now, I can add messages only in messages or threadRequest. That means I have to re-call every time the CreateThreadAndRunAsync in order to update the chat with the user?

[StephenHodgson]

your messages variable is your local copy. You'll need to get the latest messages from the thread.